Yes. At start I created very long text and decided to split it in three pieces. Topics cross each other a little.
Ability to auto-update geometrical inputs would be a huge relief. But also with an “embedded” option so I can safely remove inputs. Maybe deleting live-linked input geometries would just convert inputs into embedded ones and moving elements would throw a warning.
Rest of the topic with Human UI I will leave for different occasions. On the forum, there are plenty of examples showing how sophisticated custom UI people are building for themselves. I thought it was worth mentioning.
Because Human UI can preview geometry, there could be multi-step visual guidance in the “Human UI VA GH Style Properties” which would help to visualize the logic of VA Object creation.
It could show a simplified view with general settings, and a separate view with parameters for the details.
Are you familiar with the long PDF documentations for the Revit Families which are describing which parameter does what? 
Horrible.